Hydrogenated bisphenol A (HBPA), also called 2,2-bis(4-hydroxycyclohexyl) propane, is an important reagent in the production of various polymers and engineering plastics. HBPA or its derivatives can be reacted with appropriate acids, amines, etc. to produce, for example, polyesters, polyamides and phenolic polymers. Numerous U.S. patents, e.g. U.S. Pat. Nos. 4,214,040; 4,179,420; 4,102,944; 4,016,112; and 3,956,228, describe the use of HBPA in polyester production alone.
Generally, HBPA-based polymers are produced by reacting a difunctional HBPA-based ingredient with co-reactants having a functionality of two or more. The resultant polymers are linear or cross-linked molecules. Since the co-reactants have two or more sites for reaction, it is important to insure that the presence of monofunctional impurities--which would be chain terminators--is kept at a minimum. Accordingly, it is desirable that monofunctional impurities commonly associated with HBPA, i.e., phenols and mono-hydric alcohols, be removed therefrom before the HBPA is employed to produce polymers.
Additionally, it is well known that the trans, trans isomer of HBPA is more valuable than its other isomers. It has been observed that reaction of the high-melting trans, trans isomer yields polymers having more symmetry and better physical properties, e.g., higher melting points.